1. Field of the Invention
The present invention relates to a wireless communication system. In particular, the present invention relates to an effective buffer management apparatus and method for a Hybrid-Automatic Repeat reQuest (HARQ) scheme in a wireless communication system.
2. Description of the Related Art
A Hybrid Automatic Repeat reQuest (HARQ) scheme is employed to increase data transmission efficiency in a current wireless communication system and a next generation wireless communication system such as 3rd Generation Partnership Project Long Term Evolution (3GPP LTE), Worldwide Interoperability for Microwave Access (WiMAX), etc. The HARQ scheme is proposed to correct a data error in a more rapid manner.
While the conventional Automatic Repeat reQuest (ARQ) scheme determines whether to retransmit reception data by determining an error of data received in a software manner, the HARQ scheme determines whether to perform retransmission by determining the error of the reception data in a hardware manner. Therefore, a system employing the HARQ scheme can rapidly detect an error of received data. In addition, higher reception performance can be obtained by combining Log Likelihood Ratio (LLR) values of retransmitted data and initially transmitted data.
In a next-generation communication system such as the aforementioned LTE and WiMAX, there is a tendency that a maximum data reception rate defined by a communication protocol for the HARQ scheme has gradually increased in recent years. Accordingly, a memory overhead is significantly great due to an increase in an HARQ reception rate when a modem is designed according to a protocol of the LTE, WiMAX, etc. Further, even if a memory of which a size is sufficient for the modem is ensured, it is difficult to design the modem when considering power consumption, a chip size, etc.
Accordingly, there is a need for a method of minimizing a required memory size and also minimizing power consumption by effectively using a memory when applying an HARQ scheme.